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JSON Formatter and Validator

Paste JSON to pretty-print it, minify it, or find exactly where it's broken. Your data is processed in your browser and never uploaded.

Processed in your browser. Safe for API keys, tokens and customer data – nothing is sent anywhere.

How to format and validate JSON

  1. Paste your JSON into the left box, or press Try an example to see how it works.
  2. Check the status under the box. A green tick means the JSON is valid. If there's an error, you'll see its line, column and a pointer to the exact spot.
  3. Choose Format or Minify, and pick 2 spaces, 4 spaces or tabs for indentation. Switch on Sort keys A–Z to order object keys alphabetically.
  4. Copy or download the result from the right-hand box.

Features

  • Instant formatting as you paste, with no button to press.
  • Precise error messages, with line and column numbers and the problem line highlighted.
  • Minify to the most compact valid JSON.
  • 2-space, 4-space or tab indentation.
  • Recursive key sorting for clean diffs and easier reviews.
  • Size before and after, so you can see how much minifying saves.
  • Copy to clipboard and download as .json.
  • Handles large files smoothly without freezing the page.

Why use Fileora's JSON formatter

Developers paste some of their most sensitive data into JSON formatters: API responses containing customer details, JWTs, configuration files with secrets. Many online formatters send that data to a server. Fileora doesn't. It uses the JSON parser built into your browser, so the data never leaves your machine, and the page keeps working even if you go offline after it loads.

It's also fast and uncluttered, with the input and output side by side on a laptop and stacked on a phone. There's no account and no daily limit.

Other developer-friendly tools on Fileora: generate a strong secret with the password generator, count characters in a payload or message with the word counter, or turn a URL into a QR code.

Common JSON mistakes

The most frequent error is a trailing comma after the last item in an object or array, which JavaScript allows but JSON doesn't. Next come single quotes: JSON strings and keys must use double quotes. Unquoted keys like {name: "x"} are also invalid. Inside strings, line breaks and tabs must be escaped as \n and \t, and backslashes as \\. Finally, JSON has no undefined, NaN or comments: use null instead of a missing value, and remove comments before parsing.

Frequently asked questions

How do I format JSON?

Paste your JSON into the left box. If it's valid, the formatted version appears on the right straight away, indented with 2 spaces by default. Choose 4 spaces or tabs from the Indent menu, then copy the result or download it as a .json file.

How do I find an error in my JSON?

If the JSON is invalid, the tool shows the line and column where parsing stopped, the browser's explanation, and the offending line with a caret (^) under the problem. Common causes are a trailing comma, a missing quote, single quotes instead of double quotes, or an unescaped character inside a string.

Is it safe to paste API keys or customer data?

Yes. Formatting and validation happen entirely in your browser using its built-in JSON parser. Nothing is sent to our servers or logged, so you can safely paste API responses, tokens and configuration files.

What does minify do?

Minifying removes every unnecessary space and line break, producing the smallest valid JSON. It's useful for storing JSON in environment variables, sending smaller payloads, or embedding JSON in HTML. The data itself is unchanged.

What does sort keys do?

It reorders the keys of every object alphabetically, at every level of nesting. That makes it much easier to compare two JSON documents or to review changes, because the same keys always appear in the same order. Array order is never changed.

Does it support JSON with comments?

No. Standard JSON doesn't allow comments or trailing commas, and this tool validates against the standard, so you'll see an error. Remove the comments first, or check whether your tool expects JSON5 or JSONC instead of plain JSON.

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